[Drug-induced interstitial lung diseases]

Pulmonary drug reactions are a relatively common factor causing interstitial pulmonary disease. Histological findings of pulmonary drug reactions can mimic other conditions such as various forms of idiopathic interstitial pneumonia such as nonspecific interstitial pneumonia, organizing pneumonia, diffuse alveolar damage, or usual interstitial pneumonia. The correct diagnosis is important since a causal therapy is possible by stopping the administration. A stringent correlation between dose/time of administration and the type of reaction exists for only a few drugs. An increased risk of drug side effects can arise from known reactions to that specific drug, the patient's history, the type of underlying disease, genetic polymorphisms, occupational factors, and interactions with other drugs. The identification of a pulmonary drug reaction is a difficult task that can often only be solved in an interdisciplinary manner, for which in rare cases a lung biopsy is necessary. Pathology then has to identify histomorphological reaction patterns to exclude other causes and correlate findings with clinical data. In most cases, however, the diagnosis of a drug reaction will be by exclusion.